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pole barn sub panel
Eric,
I thought I sent this from dial up connection but it did not make it.
In going over what you first asked, I have a question. Your two hot wires are 220 voltage across them, correct? If you used a side by side double breaker they should be 220. If you used a piggy back or two single breakers that are not side by side you may have both hot wires on the same leg of your main breaker box. If you do you only have 110 voltage and you are placing a double load on your single neutral. THAT WOULD BE DANGEROUS AND ONE DAY WILL FAIL.
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pole barn sub panel
Kthompson, my sub is fed by a 30amp double pole breaker.
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pole barn sub panel
My best suggestion would to contact a good local electrician , the reason they make code rules is because someone before you has found out the hard way the wrong way to wire something.
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pole barn sub panel
Eric,
I thought you probably had but I have seen the other done.
I hope you enjoy your barn.
As to codes there is reasons for them. Some even make a lot of sense which I fully agree. Now why was the code for years on a 110 circuit a power and a neutral or the black and white wire only? Then there came the smaller guage ground and then it was decided the ground must be as large as the power.
At the same time there was code requirement for the 110 circuit to have the third wire the ground as the same guage as the power and neutral the code also said if you were to replace the outlet itself in an old 2 wire circuit you were to use or at least allowed to use the 3 prong outlet giving the impression to someone using it to be a grounded outlet. Now if that makes sense I forgive those who make codes and think they are perfect. Some of the electric codes (last I studied them) were a lot like some of the IRS code, law but huh?
As to a good local electrician, please if you do, do ask more at least two and let us know if both gave the exact same answer. Now, let one be about 30 and one about 60. Don't forget to ask how many barns, houses or what ever each has wired and then how many have burnt due to wiring.
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pole barn sub panel
there is specific chapters in the nec on multi.outbuildings for farm use. local codes will superseed nec. for nec specs you do not need the ground wire for each building they will be treated as own sep. service and 2 grounds 6 feet apart. 6 throws of the hand still applies for any service.
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pole barn sub panel
You should run a fourth wire (also #8) for the ground wire. Since the 30 amp circuit normally will be used to power other 15 or 20 amp circuits, a small 4 - 8 circuit breaker panel (without a main breaker is about $15 (plus $3/breaker) is required at the barn. It is also necessary to have a separate ground buss (normally purchased separately from the panel) for all ground returns. It is never permitted to use the neutral and ground busses tied together in a sub panel such as you are installing. Barn circuits should be protected by 15A or 20A GFCI circuits ($10) unless they are for (and ONLY for) dedicated fixed equipment. It is not expensive to conform to the NEC and much safer for everyone. The breakers allow you to turn off each circuit and the 30A breaker in the main panel allows you to disable the entire sub-panel in the barn. The correct wiring of ground and neutral wires allows the GFCI protectors to prevent shocks with nearby water and wet soil or concrete and are required.
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pole barn sub panel
It is never permitted to use the neutral and ground busses tied together in a sub panel such as you are installing.
Actually it is permitted. Nec does state this, and was also confirmed by an electrician.
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The reason the NEC was changed was to be certain that ground fault interrupt devices would operate properly from sub-panel circuits and to prevent poor bonding to the neutral wire which can easily create a shock hazzard in damp locations. This separates the requirements for grounding and bonding at sub-panels. Metal pipes or ground rods are bonding to the ground (not the neutral) buss in the sub-panels.
A good internet reference on NEC Article 250.4 is located at "http://www.iaei.org/magazine/03_f/03_f_threechiefs.htm". It describes the installation detailed in the first post and provides step by step details on adding the fourth (ground wire) and why the isolation must be done in existing installations.
Link:
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pole barn sub panel
That is true. Since I have only three feeds two hots and a neutral to the detached structure this is why I must bond the panel. If I don’t bond it and I have a ground fault more then likely this would not trip the breaker in the barn since earth is a terrible conductor of electricity. Now with me bonding the neutral and ground the ground fault will travel back to my main panel via the neutral which will give it enough resistance to trip the breaker. This is why I must bond the panel in the pole barn.
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pole barn sub panel
I am in Ky and wired my pole barn in 2004. The inspector told me to run two hot and one neutral to the barn to a panel with a 100amp breaker that feeds a box for 8 breakers. He said I do not need a bare ground wire with the service line to the barn nor a grnd rod to ground the service at the barn. The service is set up with an isolated neutral and the bare wires grounded to the breaker boxes. The two breaker boxes are bolted and grounded to each other. Ky addopted the 2005 NEC code in 2005 so it may be different now. I am going to ask around and see if I need a ground rod and any changes to the way it is hooked up. I am very currious and interested about this now.
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12-01-2005, 08:07 
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